This application claims the priority of German patent document No. 10 2004 006 070.3, filed Feb. 7, 2004, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and apparatus phase balancing of amplifier modules.
When the power output of several parallel connected amplifier modules is to be combined (for example, in a Wilkinson adder), the phase of the amplifier control must be balanced beforehand, so that the total power output will be the sum of the individual outputs. Conventionally, this has been done by matching the phasing of the several amplifier modules with a reference amplifier module. Balancing is performed such that the amplifier modules were produced corresponding to a model (reference amplifier module). During the manufacturing, the output phases of the individual amplifier modules are substantially adapted by virtue of constructional methods.
One disadvantage of this method is that it requires increased balancing expenditures in the series production of components with several parallel connected amplifier modules. Another disadvantage is that phase errors (which occur, for example, because of temperature changes or aging) cannot be compensated.
It is therefore an object of the present invention to provide a phase balancing method that permits a simple phasing for several parallel connected amplifier modules.
Another object of the invention is to provide a circuit for implementing the method.
These and other objects and advantages are achieved by the method and apparatus according to the invention, in which an amplifier module is defined as a reference module with a fixed phase, in a first step. In a second and in subsequent steps, the phases of the other amplifier modules are adjusted in pairs relative to the reference module defined in the first step, such that the combined power output from the respective individual amplifier module and the reference module is minimized. In a last step, the phase of the reference module is shifted by 180°.
A circuit according to the invention for balancing the phases of a number of amplifier modules comprises a signal source which is assigned to each amplifier stage. Advantageously, a digital interface exists which is connected with the signal source.
One advantage of the method according to the invention is that phase matching of the amplifier modules to a separate model-type reference module is not required during the manufacturing. The amplifier modules can expediently be transmitter modules in an antenna system.
Another advantage is that phasing can be performed essentially automatically. In addition, the method according to the invention makes it possible to compensate for phase deviations which occur, for example, due to temperature changes or aging or the exchange of an amplifier module.
It is another advantage that the phase balancing can take place in the continuous operation of the amplifier modules.
It is still another advantage of the method according to the invention that the result of the phasing is independent of the reference module selected in the first process step.
In an advantageous embodiment of the invention, the other amplifier modules are switched off before a phase matching between the reference module and an amplifier module. As a result, an optimal matching of the phases between the two modules is achieved.
In another advantageous embodiment of the invention, the phase for each amplifier module is digitally generated and set. As a result, more precise phase values can be set in comparison to an analog generation. In addition, the phase values can be set significantly faster digitally, so that the entire phase balancing can take place more rapidly.
Advantageously, the phase value which minimizes the combined power output from the respective individual amplifier module and the reference module is stored. As a result, the phase values can again be written into the amplifier modules, at a new system start of the amplifier modules. The phase value can of course also be written into the signal source assigned to the amplifier stage.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.